292 A TALK ABOUT SOME TREE LEAVES. [Sept. 



following out this vein of investigation. But even local instances 

 testify how exposure to sunlight and other meliorating physiographic 

 influences may further plant development, of course including leaf- 

 perfecting. A fortnight since we observed in the outskirts of Stirling, 

 in the grounds of a villa sheltered by the high crags at the west of 

 the King's Park, a Picca whose leaves and branches out from a 

 sheltering crag showed abnormal luxuriance, whilst those lying 

 towards it were but half developed. Then too a change of leaf-form 

 with varied conditions of growth is shown in young hollies which 

 have spring leaves, thus protecting them from browsing raids by 

 young animals, while the leaves of the older trees are quite unarmed. 

 Then again, Mr. Bunbury demonstrated how evergreen oaks, when 

 kept low, form scrubby bushes with hard prickly leaves. 



The balsam poplar has its lower side covered with thick hairy 

 down, thereby coinciding with several other balsams which either 

 for a time, or throughout life, have such protecting covering. If it 

 is to protect the plants against snow, the hazels may also be ranked 

 as having likewise in common such armour. But insects may be 

 attracted to the under surface of the balsam poplar from whose pale 

 yellow leaves in spring comes such a rich fragrance as to render 

 i\, attractive to grouse and other game birds in coverts, which 

 are said to show traces of such feeding even at table. The Imlsam 

 poplar has a variety called candicans, syn. P. Ontaricnsis, Balm of 

 Gilead poplar, in which the leaves are broader and cordate, or heart- 

 shaped, at the base. So, in fine, the poplar family may afford 

 many other instances in which leaf-form may depend on position, 

 as it flourishes along the whole area of the temperate zone ; and 

 observers may farther note abnormal forms in specific localities even 

 in this country, where local position, or the prevalence of insects, 

 etc., may be also peculiar. Perhaps the leaves of Gorylus avcUana 

 (Plate iv. fig. 1) and of Corylus colurna (Plate iv. fig. 2) may be 

 useful for preliminary training in such woodland studies. Both 

 have come from the far east, yet they seem specially adapted in 

 their present forms to withstand the snows of wintry latitudes. 

 Here they are objects inspiring the sense of the beautiful all through 

 the year, from February till the first touch of frost, when they don 

 the rich yellow colour only to be put off again in early spring. If 

 the broad spread of the hazel leaves given in our plate indicate 

 adaptability for a horizontal sheltering position, so also does the 

 form of the aspen poplar leaf, as will be seen in a plate to accompany 

 our next issue. 



